Casting of deoxidized copper

ABSTRACT

Apparatus comprising conductivity measuring probe for measuring the conductivity of copper casting, measuring apparatus for determining the difference between the measured conductivity and a predetermined conductivity, and means for producing a signal proportional to the difference and transmitting the signal to a regulator which regulates the amount of deoxidizer added to molten copper.

[75] Inventor:

United States Patent [191 De Bie CASTING 0F DEOXIDIZED COPPER Edouard DeBie, Antwerpen, Belgium [73] Assignee: Metallurgie Hoboken-Overpett,Brussels, Belgium [22] Filed: Aug. 15, 1972 211 Appl. No.: 280,917.

[52] US. Cl. 164/154, 164/266 [51] Int. Cl 822d l/02 [58] Field ofSearch 164/4, 56, 150, 154,

[56] References Cited UNITED STATES PATENTS 3,614,978 l0/l97l Koscol64/l54 i i 3,785,427 I Jan. 15, 1974 3,358,743 12/1967 Adams 164/154Primary ExaminerJ. Spencer Overholser Assistant ExaminerJohn E. Roethel7] ABSTRACT Apparatus comprising conductivity measuring probe formeasuring the conductivity of copper casting, measuring apparatus fordeterm ining the difference between the measured conductivity and apredetermined conductivity, and means for producing a signalproportional to the difference and transmitting the signal to aregulator which regulates the amount of deoxidizer added to moltencopper.

8 Claims, 2 Drawing Figures This invention relates to the casting ofdeoxidized copper and more particularly. to a process for the continuousmeasuring of the conductivity of a copper casting, for instance of acopper billet, or plate, cast either continuously or semi-continuously.It is known that conductivity is one of the important proporties ofcopper trade products and that this property diminishes according to anincrease in the contents of impurities.

In copper which has been d'eoxidized, for instance by means ofphosphorous, it is the phosphorous that will have the greatest impact onconductivity since the other impurities are limited to a few grams perton.

Hence, there is a relation between the conductivity and thephosphorous-content; if the conductivity of a deoxidized copper isknown, its phosphorous-content can be determined.

There is a well-known method for measuring the conductivity according tothe principle of magnetic induction and Foucault currents.

In daily practice, a melting furnace supplies liquid copper to a holdingfurnace, which in its turn feeds a continuous casting plant. In order toobtain deoxidized copper, a deoxidizer, generally phosphorous or aeuprophosphorous alloy, is added, usually to copper flowing into theholding furnace. Such addition is done either continuously ordiscontinuously. The flow of deoxidizer is determined by the followingparameters quality required for the cast product, average casting flow,and average or probable oxygen content of the liquid copper leaving themelting furnace.

The quality of the product is controlled, after sawing and transport, ata controlstation. The inspector of the continuous casting line controlsthe phosphorous contents of billets or the like by measuring regularly,for instance on one billet out of 'two, the conductivity by putting theconductivity measuring probe on a sawn surface of the billet and informsthe casting operator step by step of the results, and theoperatoradjusts accordingly the phosphorous quantity added to the cast ing.

However rapid this method may be, it has several drawbacks, especiallywhen billets are cast continuoulsy. The measuring is donediscontinuously, and if the metal is not perfectly homogeneous themeasuring might give a wrong idea of the average phosphorous content.Furthermore, the measuring is only done at a relatively far distancefrom the place where the casting isdone, for instance several metersafterthe casting. Consequently, the phosphorous contents are checkedwith a considerable delay, especially when big sizes are cast, with theresult that a divergence in the determination of the phosphorousaddition involves several tons of rejects. It is therefore practicallyimpossible to effect a subsequent control of the regularity of additionand efficiency of a reaction. Moreover, each measure entails sawingbillet slices which must be recycled. The invention provides apparatusfor controlling the addition of deoxidizer to molten copper duringcopper casting comprising a conductivitymeasuring probe for continuouslymeasuring the conductivity of casting as it moves past the probe,measuring apparatus for determining the difference between the measuredconductivity and a predetermined conductivity, and means for producing asignal proportional to the said difference and transmitting said signalto a regulator which regulates the amount of deoxidizer added to themolten copper.

The measuring is effected according to the invention on the skin of thepiece of copper, no longer on a sawn surface of the piece of copper.Tests have shown that there is a difference between measurementsobtained on the skin and those on the sawn surface of the copper.

This apparatus enables a continuous measuring of the conductivity of acontinuously cast copper piece to be made; the measuring is effected atthe exit of the casting line, after the copper piece has been cooled.

Preferably, the conductivity measuring probe is mounted on roller meansadapted to contact the casting moving therepast during casting.

With the above-described apparatus, a measuring of the conductivity canbe carried out much more rapidly, thus permitting a quicker reaction ofthe operator in the case of an anomaly in the phosphorous-content, toadapting that content to the conductivity control value. Since thetendency of the phosphorous-content is clearly registered, it ispossible to anticipate overstepping the set phosphorous limits and toreduce thus the number of rejects.

The phosphorous addition can also be brought automatically under controlof the conductivity measuring, for instance by making the measure actupon a dosage device, for instance upon ameasuring feed hopper in whichthe phosphorous to be added to the liquid copper is stored.

Preferably, correction means are provided for automatically correctingthe conductivity measured by compensating for the differences betweenthe temperature recorded on the casting and the temperature chosen for arequired conductivity value.

Preferably, the regulator is controlled by means for measuring theoxygen contentof the molten copper before casting and means formeasuring the flow of molten copper.

Preferably, the flow of molten copper is determined from themeasurements of means measuring the flow of the solidified casting andmeans measuring the weight variation of the molten copper being cast ina holding furnace.

The invention will be further described with reference to an embodimentshown by way of example in the accompanying drawings, wherein FIG. 1 isa longitudinal cross-section of the continuous casting plant used in thepresent invention and.

FIG. 2 is a diagrammatical vertical view of the main part of the deviceaccording to the invention.

Referring to FIG. 1, a melting furnace 1 supplies liquid copper to aholding furnace 3 via a spout 2.

The copper is cast in a moulds. The cast product 4 passes through acooling tank 6 and is moved by means of extraction rolls 7.

The casting speed is measured at 8 and is transmitted to a regulator 15.

A conductivity probe 9 transmits a continuous signal to a measuringapparatus 10. The measuring apparatus 10 transmits a signal proportionalto the conductivity to the recorder 11 and to the regulator 15.

The signal is previously amplified in an amplifier 29 where it undergoesa temperature correction produced by a temperature probe 30.

A probe 16, which is for measuring oxygen content and is dipped in thecopper of the spout, transmits a continuous signal to a signal converter17, which in its turn transmits the value of the oxygen content of theregulator 15.

Weighing apparatus 12 measures the weight of the holding furnace 3. Asignal proportional to the weight of the copper contained in the saidfurnace is also transmitted to the regulator 15, via the measuringapparatus l3 and transmitter 14.

On the basis of these various measurements, the regulator 15 determinesthe flow of deoxidizer which is necessary in order to obtain the qualityrequired, as set by a control 20. To this end, the regulator 15 acts forinstance upon the speed of a driving motor 18 of the apparatus 19 whichdelivers the deoxidizer.

In FIG. 2, a copper billet, the conductivity of which, and hence thephosphorous content, is measured, has been shown at 4.

The conductivity probe 9 is mounted on roller means in the form ofacarriage 21, the wheels 22 of which rest upon the billet 4. The bearingpressure is obtained by the carriages own weight and by a counterweight23 provided on an arm or bar 24 which pivots about a fixed axis 25. Thebillet 4 can thus run smoothly against the carriage 21, and anyvibrations caused by the casting table and the saw (not illustrated) arenot transmitted to the measuring device.

The distance between the probe 9 and the billet 4 can be adjusted bymeans of nuts 26, so that the position of the probe 9 can be adapted toa billet of any diameter. The probe 9 is electrically connected to aconductivity measuring apparatus 10.

Under practical working conditions, the movement of a needle 28, whichis mounted in the measuring apparatus 10, is proportional to thedifference between the measured conductivity and a predeterminedconductivity value set on a dial 27. If desired, the dial 27 may also becalibrated for phosphorous percentage content. A signal which isproportional to the movement of the needle 28 is amplified in anamplifier 29 and is transmitted, after temperature compensation by meansof the temperature measuring probe 30, to the recorder 11 and to theregulator 15.

The probe 30, which is mounted on the carriage 21, measures thetemperature of the billet 4 and enables compensation in the amplifier 29of the signal which is proportional to the deviation of indicator 28 sothat deviation is brought back to standard temperature conditions.

What I claim is:

1. Apparatus for controlling the addition of deoxidizer to molten copperduring copper casting, comprising a conductivity measuring probe forcontinuously measuring the conductivity of casting as it moves past theprobe, measuring apparatus for determining the difference between themeasured conductivity and a predetermined conductivity, and means forproducing a signal proportional to the said difference and transmittingsaid signal to a regulator which regulates the amount of deoxidizeradded ,to the molten copper.

2. Apparatus as claimed in claim 1, wherein the conductivity measuringprobe is mounted on roller means adapted to contact the casting movingtherepast during casting.

3. Apparatus as claimed in claim 2, wherein the roller means is mountedon a pivoting arm carrying a counterweight for urging the roller meansagainst the casting.

4. Apparatus as claimed in, claim 1, comprising means for permitting theadjustment of the distance between the conductivity measuring probe andthe casting in order to permit adjustment of the position of the probeto a casting of any shape.

5. Apparatus as claimed in claim 1, wherein the conductivity measuringprobe is connected to means indicating the phosphorous percentagecontent in the copper casting.

6. Apparatus as claimed in claim 1, comprising correction means forautomatically correcting the conductivity measured by compensating forthe differences between the temperature recorded on the casting and thetemperature chosen for a required conductivity value.

7. Apparatus as claimed in claim 1 wherein the regulator is controlledby means for measuring the oxygen content of the molten copper beforecasting.

8. Apparatus as claimed in claim 7, having means for measuring the flowof molten copper by measuring the flow of the solidified casting andmeans are provided for measuring the weight variation of the moltencopper which is cast in a holding furnace.

1. Apparatus for controlling the addition of deoxidizer to molten copperduring copper casting, comprising a conductivity measuring probe forcontinuously measuring the conductivity of casting as it moves past theprobe, measuring apparatus for determining the difference between themeasured conductivity and a predetermined conductivity, and means forproducing a signal proportional to the said difference and transmittingsaid signal to a regulator which regulates the amount of deoxidizeradded to the molten copper.
 2. Apparatus as claimed in claim 1, whereinthe conductivity measuring probe is mounted on roller means adapted tocontact the casting moving therepast during casting.
 3. Apparatus asclaimed in claim 2, wherein the roller means is mounted on a pivotingarm carrying a counterweight for urging the roller means against thecasting.
 4. Apparatus as claimed in claim 1, comprising means forpermitting the adjustment of the distance between the conductivitymeasuring probe and the casting in order to permit adjustment of theposition of the probe to a casting of any shape.
 5. Apparatus as claimedin claim 1, wherein the conductivity measuring probe is connected tomeans indicating the phosphorous percentage content in the coppercasting.
 6. Apparatus as claimed in claim 1, comprising correction meansfor automatically correcting the conductivity measured by compensatingfor the differences between the temperature recorded on the casting andthe temperature chosen for a required conductivity value.
 7. Apparatusas claimed in claim 1 wherein the regulator is controlled by means formeasuring the oxygen content of the molten copper before casting. 8.Apparatus as claimed in claim 7, having means for measuring the flow ofmolten copper by measuring the flow of the solidified casting and meansare provided for measuring the weight variation of the molten copperwhich is cast in a holding furnace.